Novel one-step method for the conversion of isothiocyanates to 2-alkyl(aryl)aminothiazoles

2-Aminothiazole derivatives are widely used structural motifs in medicinal chemistry due to their broad application in drug development. Herein we demonstrate a novel one-step method for the synthesis of 2-aminothiazole derivatives from the corresponding isothiocyanates via thiourea formation followed by cycloisomerisation in an intramolecular thia-Michael fashion. This method is very mild, simple and highly efficient and versatile enough to accommodate various amino substitutions at the C2 position of thiazoles. This methodology is equally well applicable to synthesise various 2-substituted amino-5-thiazolylmethylphosphonate derivatives.     

Chemical synthesis of zinc oxide nanorods for enhanced hydrogen gas sensing

Zinc oxide(ZnO) nanorods are prepared using equimolar solution of zinc nitrate((Zn(NO3)2) and hexamethylenetetramine(C6H12N4) by the hydrothermal technique at 80 C for 12 h. Epitaxial growth is explored by X-ray diffraction(XRD) patterns, revealing that the ZnO nanorods have a hexagonal(wurtzite) structure. Absorption spectra of ZnO are measured by UV–visible spectrometer. The surface morphology is investigated by field emission scanning electron microscopy(FESEM). The synthesized ZnO nanorods are used for detecting the 150 C hydrogen gas with a concentration over 1000 ppm. The obtained results show a reversible response. The influence of operating temperature on hydrogen gas detecting characteristic of ZnO nanorods is also investigated.     

Anti-Inflammatory CeO2 Nanoparticles Prevented Cytotoxicity Due to Exogenous Nitric Oxide Donors via Induction Rather Than Inhibition of Superoxide/Nitric Oxide in HUVE Cells

The mechanism behind the cytoprotective potential of cerium oxide nanoparticles (CeO₂ NPs) against cytotoxic nitric oxide (NO) donors and H₂O₂ is still not clear. Synthesized and characterized CeO₂ NPs significantly ameliorated the lipopolysaccharide (LPS)-induced cytokines IL-1β and TNF-α. The main goal of this study was to determine the capacities of NPs regarding signaling effects that could have occurred due to reactive oxygen species (ROS) and/or NO, since NP-induced ROS/NO did not lead to toxicity in HUVE cells. Concentrations that induced 50% cell death (i.e., IC50s) of two NO donors (DETA-NO; 1250 ± 110 µM and sodium nitroprusside (SNP); 950 ± 89 µM) along with the IC50 of H₂O₂ (120 ± 7 µM) were utilized to evaluate cytoprotective potential and its underlying mechanism. We determined total ROS (as a collective marker of hydrogen peroxide, superoxide radical (O₂^•−), hydroxyl radical, etc.) by DCFH-DA and used a O₂^•− specific probe DHE to decipher prominent ROS. The findings revealed that signaling effects mediated mainly by O₂^•− and/or NO are responsible for the amelioration of toxicity by CeO₂ NPs at 100 µg/mL. The unaltered effect on mitochondrial membrane potential (MMP) due to NP exposure and, again, CeO₂ NPs-mediated recovery in the loss of MMP due to exogenous NO donors and H₂O₂ suggested that NP-mediated O₂^•− production might be extra-mitochondrial. Data on activated glutathione reductase (GR) and unaffected glutathione peroxidase (GPx) activities partially explain the mechanism behind the NP-induced gain in GSH and persistent cytoplasmic ROS. The promoted antioxidant capacity due to non-cytotoxic ROS and/or NO production, rather than inhibition, by CeO₂ NP treatment may allow cells to develop the capacity to tolerate exogenously induced toxicity.     

MHD natural convective flow through a porous medium in a square cavity filled with liquid gallium

This article contains a computational study of free convective flow through a square enclosure filled with liquid gallium saturated porous medium in the presence of a uniform inclined magnetic field. Lower boundary of enclosure is considered to be heated uniformly, upper horizontal boundary is taken insulated, left wall of the cavity is heated linearly, and right wall is heated linearly or taken cold. Navier–Stokes equations governing the flow problem are first exposed to penalty method to eliminate the pressure terms and then Galerkin FEM is employed to solve reduced equations. Grid independent results are achieved and shown in tabular form for numerous ranges of physical flow parameters. To ensure the accuracy of developed code, computed results are compared with those available in earlier studies through figures. It is found that the strength of streamlines circulation is increased due to increase in Darcy number while imposition of vertical magnetic field instead of horizontal magnetic field causes slow rate of increase in strength of streamlines circulation. Whereas, in the case of linearly heated right wall, the average Nusselt number is an increasing function of the Darcy number, and vertical magnetic field causes higher values for average Nusselt number as compared to horizontal magnetic field along bottom and side walls of cavity. Contrarily, in the case of cold right wall, the horizontal magnetic field results in higher values of average Nusselt number as compared to the vertical magnetic field case, and the average Nusselt number reduces as we move along lower and right boundary while increases along left wall with increase in distance.     

Mixed convection flow of a micropolar fluid over a non-linearly stretching sheet

The steady two-dimensional mixed convection flow of a micropolar fluid over a non-linear stretching sheet is investigated. The governing non-linear equations and their associated boundary conditions are transformed into coupled non-linear ordinary differential equations. The series solution of the problem is obtained by utilizing the homotopy analysis method (HAM). The convergence of the obtained series solutions is carefully checked. The physical significance of interesting parameters on the flow and the thermal fields are shown through graphs and discussed in detail. The values of wall shear stress, couple wall stress and the local Nusselt number are tabulated. Comparison is also made with the corresponding results of viscous fluid with no mixed convection and an excellent agreement is noted.     

Structural,electrical and magnetic properties of Zr–Mg cobalt ferrite

Spinel cobalt ferrite, CoFe_2−xM_xO₄ has been synthesized by substitution of the combination of metallic elements M=Zr–Mg by the microemulsion method using polyethylene glycol as a surfactant. Powder X-ray diffraction analysis reveals that the substitution results in shrinkage of the unit cell of cobalt ferrite due to higher binding energy of the synthesized samples. The energy-dispersive X-ray fluorescence analysis confirms the stoichiometric ratios of the elements present. The thermogravimetric analysis shows that the minimum temperature required for the synthesis of these substituted compounds is 700 °C. A two-point probe method was employed for the measurement of the electrical resistivity in a temperature range of 293±5 to 673±5 K. It appears that there is a decrease in the number of Fe²⁺/Fe³⁺ pairs at the octahedral sites due to the substitution and corresponding migration of some of the Fe³⁺ ions to tetrahedral sites, consequently increasing the resistivity and the activation energy of hopping of electron at the octahedral sites. The susceptibility data also suggest migration of Fe³⁺ to tetrahedral site in the initial stage, which results in an increase in A–B interactions leading to large increase in the blocking temperature (T_B) as observed in samples having dopant content x=0.1.     

ZnO-Templated Selenized and Phosphorized Cobalt-Nickel Oxide Microcubes as Rapid Alkaline Water Oxidation Electrocatalysts

Oxygen electrocatalysis is of remarkable significance for electrochemical energy storage and conversion technologies, together with fuel cells, metal-air batteries, and water splitting devices. Substituting noble metal-based electrocatalysts by decidedly effective and low-cost metal-based oxygen electrocatalysts is imperative for the commercial application of these technologies. Herein, a novel strategy is presented to fabricate selenized and phosphorized porous cobalt-nickel oxide microcubes by using a sacrificial ZnO spherical template and the resulting microcubes are employed as an oxygen evolution reaction (OER) electrocatalyst. The selenized samples manifest desirable and robust OER performance, with comparable overpotential at 10 mA cm⁻² (312 mV) as RuO₂ (308 mV) and better activity when the current reaches 13.7 mA cm⁻². The phosphorized samples exhibit core–shell structure with low-crystalline oxides inside amorphous phosphides, which ensures superior activity than RuO₂ with the same overpotential (at 10 mA cm⁻²) yet lower Tafel slope. Such a surface doping method possibly will provide inspiration for engineering electrocatalysts applied in water oxidation.     

Exact solution to peristaltic transport of power-law fluid in asymmetric channel with compliant walls

Effects of compliant wall properties on the peristaltic flow of a non-Newtonian fluid in an asymmetric channel are investigated.The rheological characteristics are characterized by the constitutive equations of a power-law fluid.Long wavelength and low Reynolds number approximations are adopted in the presentation of mathematical developments.Exact solutions are established for the stream function and velocity.The streamlines pattern and trapping are given due attention.Salient features of the key parameters entering into the present flow are displayed and important conclusions are pointed out.     

Goos–Hänchen Shift from Cold and Hot Atomic Media Using Kerr Nonlinearity

We study and examine the Goos–Hänchen shifts of a propagating probe light field in a four-level tripodtype cold and hot atomic medium. The behavior of Goos–Hänchen shifts is studied in reflection and transmission beams in the presence of the coherent Kerr effect and the Doppler broadening effect. We observe that these shifts can be controlled by the relative propagation direction of the control field to that of the probe field.     

On the Chromaticity of Quasi Linear Hypergraphs

An h-hypergraph H is said to be quasi linear if every two edges of H intersect in 0 or r vertices (r ≥ 1 and h ≥ 2r + 1). The main result of this paper is the following: if G and H are chromatically equivalent h-hypergraphs, H is quasi linear and h ≥ 3r ? 1, then any two edges of G intersect in 0,1 or r vertices and the result cannot be strengthened. This extends the corresponding result of the first author for linear hypergraphs (case r = 1) [Tomescu in J Combin Theory B2 72: 229–235, 1988]